OK, the Jack Black part is obvious; Cordon is chubby and cheery. But Astaire? “Rap and dance are what I want to be known for .... I’m going to do ballet or tap or modern on tour,” Corden said.

He’s joking about that, but the guy really has ranged from rap to Broadway. “He’s an actor, he’s a writer, he’s a performer,” Tassler said. “He’s a singer, he’s a dancer .... He’s pretty magic.”

And he seems to do all of it with enthusiasm.

Talk-show hosts have often kept a cool distance from their guests and their viewers. Corden describes that in positive terms: “I was amazed at how relaxed (Letterman) was,” he said. “There is a formal informality, if you like, to his approach in dealing with you.”

Still, that’s not Corden’s style. He praises “Jimmy Fallon’s ... absolute core enthusiasm” and says: “We want to make a warm show, ... a show that never feels spiky.”

Corden, 36, has middle-of-the-road roots. “I’m from High Wycombe, which you’ve never heard of, in Buckinghamshire” which we also haven’t heard of.

High Wycombe is a city of 120,000, about 30 miles west of London. Corden grew up in a town next to that; his dad was a Royal Air Force musician, his mom was a social worker and he loved performing. At 18, he had one line in a musical; next was TV, where Winston was a production assistant.

“I was 18, he was 20,” Winston recalled. “I would get them coffee and we would talk about life.”

Winston remembers seeing Corden dazzle an audience in “the most depressing club in Europe. I knew then that he was the greatest entertainer I’d ever seen.”

Two years later, Corden co-starred in “Fat Friends,” about a weekly slimming club. He and one of the stars, Ruth Jones, then wrote “Gavin & Stacey”; they gave the title roles to slim, telegenic people, writing supporting roles for themselves. “They were the more interesting parts,” he said.

The show was a hit in England. In the U.S., it aired on BBC America, then was remade with American actors as “Us & Them”; NBC shot seven episodes, which it dumped.

By then, Corden had seen an uncharacteristic failure, a sketch show that British critics attacked and viewers ignored. “I absolutely wasn’t putting the work in,” he said. “It’s a really mind-altering time, that first flash of fame, and you start to perhaps think you’re a bit more of a dude than you really are.”

He went back to work, succeeding with specials, a sports-talk-variety show and then “One Man, Two Guv’nors.” That’s a comedy play that prospered in London, then tried Broadway.

“It was so steeped in British humor, end-of-the-pier humor,” Corden said. “I remember saying to my wife, ‘Babe, there’s a real chance this isn’t going to work. So we should rent an apartment when we get to New York that we can get out of in a week.”

Instead, it ran five months; he won a 2012 Tony and audience approval. “You knew that you were in the presence of someone a little crazy and someone incredibly talented,” Tassler said.

When he pitched something else to CBS, she said, she and network boss Leslie Moonves were “mesmerized.” They asked him to take over the late-late spot Craig Ferguson has vacated.

Corden did a movie musical (“Into the Woods”), then moved to the U.S. with his wife, their 3-year-old and a newborn baby. It was time to try latenight TV — presumably with enthusiasm.

How to watch

“The Late Late Show With James Corden” airs at 12:37 a.m. weekdays, CBS, following David Letterman and opposite NBC’s Seth Meyers. Starts Monday, with Tom Hanks as guest; Reggie Watts (“Comedy Bang! Bang!”) leads the band